Anatomy And Physiology

Structure and Function of the Thyroid Gland

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"Structure and Function of the Thyroid Gland"
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The thyroid gland is a small organ located in the front of your neck. It has a relatively simple structure, yet has a complex function in regulating the metabolism of your body. This article will take a look at both the structure and function of the thyroid gland. Because function follows structure, let's begin by examining the structure of the thyroid gland.

Structure of the thyroid gland

Although quite small compared to many organs in the body, the thyroid is one of the larger glands of the endocrine system. It is located on front of the next, just below the Adam's apple. The thyroid gland has two primary lobes - the right and left. Not surprisingly, the right and left lobes are found on the right and left side of the trachea, respectively.

Connecting the right and left lobes is a small bit if tissue called the isthmus. Together, this creates a shape which vaguely resembles a butterfly.

The thyroid gland is covered in a tough fibrous capsule. This is a layer of tissue which completely surrounds the thyroid gland and protects it from the surrounding organs and tissues. The thyroid gland is immediately adjacent to the larynx and trachea. In fact, it wraps around a significant portion of the trachea.

The thyroid gland reaches his deep into the neck as the esophagus. Because the thyroid gland is made of relatively soft tissue, it can often be difficult to determine exactly how high and how low it is in a person's neck. In a fully grown adult, the thyroid gland weighs approximately 20 to 60 grams. As you can tell, the thyroid gland can vary in size greatly from person to person.

The thyroid gland receives its blood supply from the superior thyroid artery. The superior thyroid artery is a branch of the external carotid artery. some blood is also supplied by the inferior thyroid artery. This is a branch of the thyrocervical trunk. blood supply to the thyroid artery can be very important, especially to a surgeon who is forced to operate on the organ. Blood draining from the thyroid artery travels either through a superior thyroid vein or the inferior thyroid vein.

Function of the thyroid gland

The thyroid gland is a key player in the endocrine system. It produces three hormones which are vital to the metabolic function of your body. These three hormones include, thyroxine (T4), triiodothyronine (T3), and calcitonin.

T3 and T4 are extremely important to the development and subsequent metabolism of a person. T4 is relatively in active compared to T3. T4 is converted to T3 in many peripheral organs such as the liver and spleen.

The production of T3 and T4 is regulated by the pituitary gland. The pituitary gland releases a hormone called thyroid stimulating hormone, or TSH. When TSH is released, the thyroid gland begins producing T3 and T4 hormones. These hormones are then circulated around the body where they regulate the production of other proteins and cell growth.

Levels of T3 and T4 are controlled by a system known as a negative feedback loop. T3 and T4 suppress the production of TSH. So when levels of T3 and T4 become high, less TSH is produced. This in turn lowers the amount of T3 and T4 which is made. Conversely, low levels of T3 and T4 allow more TSH to be produced - which increases the amount of T3 and T4 that is made. This may seem confusing, but if you think about it for a moment it makes sense. Essentially, the hormones all serve to regulate each other.

The thyroid gland also produces a hormone known as calcitonin. Calcitonin is a vital hormone which serves to regulate the concentration of calcium in your body. Calcitonin has been found to increase the amount of calcium which is taken into bone. However, the exact importance of calcitonin in bone maintenance has not been well established, people who have had their thyroid gland removed, are able to maintain normal levels of calcium without significant treatment.

Thyroid gland requires iodine to function properly. Iodine is incorporated into the structure of T3 and T4. Without iodine, the thyroid gland is not able to make T3 and T4. a person who suffers from lack of iodine in their diet will sometimes experience a swelling of the pirate gland. A pathological swelling of the thyroid gland is referred to as a goiter. Because of its use in thyroid hormones, iodine is a key element required in the proper development of a child. This is one reason why governments have required the use of iodized salt.

There are many diseases which are related to the dysfunction of the thyroid gland. This article is not intended to go into the details of those diseases. Two of the more common diseases related to thyroid dysfunction are Graves' disease and Hashimoto's thyroiditis.

More about this author: Erich Rosenberger M.D.

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